ibwtest: command not found

Maybe Your $PATH variable doesn't contain the default paths? echo $PATH should give something like:

[root@server ~]# echo $PATH
/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin

If it's empty, You may set the PATH variable with this command

export PATH="/usr/local/sbin:/usr/local/bin:/sbin:/bin:/usr/sbin:/usr/bin:/root/bin"

On Debian possible default full paths are:

/usr/bin/ibwtest - from package: pvm-examples

You may install the required package with command apt-get install {package}

Error in other languages:
ibwtest: bevel nie gevind nie
ibwtest: comandă negăsită
ibwtest: comando não encontrado
ibwtest: commande introuvable
ibwtest: command not found
ibwtest: käsku ei ole
ibwtest: không tìm thấy lệnh
ibwtest: komanda nerasta
ibwtest: Kommando nicht gefunden.
ibwtest: kommandot finns inte
ibwtest: komut yok
ibwtest: nie znaleziono polecenia
ibwtest: níor aimsíodh an t-ordú
ibwtest: no se encontró la orden
ibwtest: no s'ha trobat l'ordre
ibwtest: opdracht niet gevonden
ibwtest: parancs nem található
ibwtest: perintah tidak ditemukan
ibwtest: príkaz nenájdený
ibwtest: příkaz nenalezen
ibwtest: команда не найдена
ibwtest: командата не е открита
ibwtest: 命令找不到
ibwtest: コマンドが見つかりません